CN106647915B - A kind of low pressure difference linear voltage regulator using digital circuit compensating electric capacity - Google Patents
A kind of low pressure difference linear voltage regulator using digital circuit compensating electric capacity Download PDFInfo
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- CN106647915B CN106647915B CN201611105561.3A CN201611105561A CN106647915B CN 106647915 B CN106647915 B CN 106647915B CN 201611105561 A CN201611105561 A CN 201611105561A CN 106647915 B CN106647915 B CN 106647915B
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/565—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor
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- General Physics & Mathematics (AREA)
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- Automation & Control Theory (AREA)
- Continuous-Control Power Sources That Use Transistors (AREA)
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Abstract
Low pressure difference linear voltage regulator is close loop negative feedback structure, the method of miller compensation can be used to ensure the stability of loop, but when the load, the equivalent Miller capacitance to adjustment tube grid changes therewith, loop dominant pole and then changes, and the stability of loop is difficult to ensure that；The present invention proposes a kind of low pressure difference linear voltage regulator using digital circuit compensating electric capacity, it is characterized in that, in the low differential voltage linear voltage stabilizer circuit using miller compensation, utilize the output voltage of voltage detecting circuit detection error amplifier, the control source digital-to-analog converter of detection is converted to data signal, the data signal inputs Digital Logic control circuit, Digital Logic control circuit judges the working condition of adjustment pipe, information according to prestoring draws the capacitance size for now needing to compensate, and output control signal, adjust the break-make of capacitor array, ensure that the total capacitance of adjustment tube grid keeps constant, so as to stablize the dominant pole of loop.
Description
Technical field
The invention belongs to IC design technical field, more particularly to a kind of low pressure using digital circuit compensating electric capacity
Difference linear constant voltage regulator.
Background technology
Low pressure difference linear voltage regulator (Low Dropout Regulator, LDO) is a kind of confession for providing regulated output voltage
Circuit, being compared with DC-DC converter has the characteristics that output voltage ripple is small, outputting current steadily, has in integrated circuits
It is widely used.
Fig. 1 is typical LDO schematic diagrams, and this is a negative-feedback circuit.As output voltage VOUTDuring rising, feedback voltage
VFRise；VFWith reference voltage VREFDifference after error amplifier AMP amplifications, obtained control voltage VCRise；And then
VOUTDecline.As load RL、CLWhen changing, output voltage VOUTBy reference voltage VREFControl, keep it is constant.
LDO design needs to consider its stability, and a kind of method is in M using miller compensation technology1The grid of pipe produces
Dominant pole.As shown in Fig. 2 electric capacity CCFor miller compensation electric capacity, resistance RCThe zero point brought for eliminating miller compensation.
Electric capacity C in miller compensationCIt is equivalent to arrive M1The size of tube grid electric capacity is equal to (A+1) CC, wherein A is by M1Pipe conduct
The absolute value of the amplifier gain of input pipe, this equivalent bulky capacitor ensure that the dominant pole of loop is located at M1The grid of pipe.So
And when LDO is loaded and changed, M1Pipe is also changing as the gain A of the amplifier of input pipe, equivalent to arrive M1The electricity of tube grid
Hold (A+1) CCAlso changing, the dominant pole size of loop is also changing, and the stability of loop is affected.
The content of the invention
The shortcomings that in order to overcome above-mentioned prior art, it is an object of the invention to provide one kind using digital circuit compensation electricity
The low pressure difference linear voltage regulator of appearance, using the working condition of compensation circuit detection LDO adjustment pipes, and electricity is controlled by Digital Logic
Road regulation is connected to the capacitance size of adjustment tube grid, and so as to ensure that grid total capacitance is constant, dominant pole frequency is constant, improves
The stability of LDO loops.
To achieve these goals, the technical solution adopted by the present invention is：
A kind of low pressure difference linear voltage regulator using digital circuit compensating electric capacity, in the low pressure difference linearity using miller compensation
In voltage regulator circuit, the output voltage of voltage detecting circuit detection error amplifier, the control source digital to analog conversion of detection are utilized
Device is converted to data signal, and data signal input Digital Logic control circuit, Digital Logic control circuit judges adjustment pipe
Working condition, the capacitance size for now needing to compensate, and output control signal are drawn according to the information to prestore, adjust capacitor array
Break-make, ensure adjustment tube grid total capacitance keep it is constant, so as to stablize the dominant pole of loop.
In the low differential voltage linear voltage stabilizer circuit using miller compensation, VOUTIt is load supplying for output voltage, etc.
Imitate load resistance RLWith equivalent load capacitance and be connected in VOUTBetween GND, pass through sampling resistor RF1With resistance RF2To VOUTEnter
Row partial pressure samples, and obtains feedback voltage VF, VFWith reference voltage VREFIt is compared, is obtained after error amplifier AMP amplifications
Control voltage VC, VCControl adjustment pipe M1Grid voltage, the electric capacity C for miller compensationCWith the resistance R for eliminating zero pointC
It is connected on VCWith VOUTBetween.
The voltage detecting circuit is connected with filter amplification circuit, and institute's detectable voltage signals are filtered, are transmitted to number after amplification
Mode converter.
The Digital Logic control circuit be connected with voltage detecting circuit it is adjusted, make its output meet digital-to-analogue become
The input requirements of parallel operation.
The capacitor array includes some groups of parallel branches, and every group of branch route an electric capacity and a switch is composed in series,
Each branch road is connected to adjustment tube grid and power supply VDDBetween, switched in each branch road of output control of the Digital Logic control circuit
Break-make so that electric capacity accesses adjustment tube grid as requested in each branch road, so as to adjust be connected to adjustment tube grid on electricity
Hold size, when the electric capacity for adjusting tube grid node becomes small, increase the capacitive branch of access so that total capacitance becomes big；Work as adjustment
When the electric capacity of tube grid node becomes big, the capacitive branch of access is reduced so that total capacitance diminishes.
The working condition of the adjustment pipe includes sub-threshold region, saturation region or linear zone.
Equivalent capacity of the adjustment pipe under different working condition is determined by circuit design early stage and emulation.
Compared with prior art, the beneficial effects of the invention are as follows the grid capacitance by adjusting pipe to LDO to compensate, can
To cause feedback control loop dominant pole frequency to be basically unchanged, so as to ensure the stability of circuit.And digital compensation circuit is used, can
More accurate to exchange the judgement of homogeneous tube working condition, the compensation method of electric capacity is more flexible.
Brief description of the drawings
Fig. 1 is simulation low pressure difference linear voltage regulator schematic diagram.
Fig. 2 is the simulation low pressure difference linear voltage regulator schematic diagram with miller compensation.
Fig. 3 is the low pressure difference linear voltage regulator schematic diagram using digital circuit compensation adjustment tube grid electric capacity.
Fig. 4 is the workflow diagram of digital control logic circuit.
Embodiment
Below in conjunction with the accompanying drawings, preferred embodiment is elaborated.It is emphasized that the description below is merely exemplary
, the scope being not intended to be limiting of the invention and its application.
In order to solve the problems, such as that the LDO dominant pole frequencies using miller compensation change with load, the present invention proposes use
The method of digital circuit compensation adjustment tube grid electric capacity.The circuit detects the grid voltage of adjustment pipe first, and the analog voltage is anti-
The working condition of adjustment pipe is reflected.Then the voltage is converted into data signal after digital-to-analog converter, in order to which numeral is patrolled
Collect control circuit processing.Then Digital Logic control circuit judges the working condition of adjustment pipe, and is drawn according to the information to prestore
Now need the capacitance size compensated.Last Digital Logic control circuit output control word, the break-make of capacitor array is adjusted, is ensured
The total capacitance for adjusting tube grid keeps constant.
It is as shown in Figure 3 that the LDO that homogeneous tube grid capacitance compensates is exchanged using digital circuit.Its main body circuit is still use
The LDO of miller compensation.Two parts of controller and capacitor array are added on this basis.
Controller includes the parts such as voltage detecting, digital analog converter (ADC), Digital Logic control and clock.LDO errors are put
Big device AMP output voltage VCVoltage detecting circuit is transmitted to, the circuit is analog circuit, by VCIt is transmitted to after signal filtering, amplification
ADC.ADC is transmitted to Digital Logic control circuit after converting analog signals into data signal.Digital Logic control circuit is according to ADC
Data judge the working condition of current adjustment pipe, and combine the information to prestore and determine now to adjust the due electric capacity of tube grid
It is worth, then control word corresponding to output.In addition Digital Logic control circuit also adjusts voltage detecting circuit, meets its output
ADC input requirements.Clock circuit then provides clock for the digital circuit in controller, the output production that the clock will not be to LDO
Raw interference.
Capacitor array includes a plurality of parallel branch, and every branch road is the series connection of switch and electric capacity, is connected on adjustment pipe M1Grid
Pole and power supply VDDBetween.The control word controlling switch S of Digital Logic control circuit output1~SNBreak-make so that electric capacity C1~CN
Access adjustment tube grid as requested.Electric capacity C1~CNQuantity and capacitance size need determined according to simulation result.
The groundwork flow of Digital Logic control circuit is as shown in Figure 4.Obtained and adjusted according to ADC output data first
The working condition of pipe.Because ADC precision can be higher, adjustment pipe can be subdivided into multiple working conditions in order to more accurately
Regulation.Then judge to adjust the change whether working condition of pipe occurs, i.e., whether need to change compensating electric capacity.If state does not have
Become, then maintain original control code；If state is changed, control code is updated with reference to prestored information.Finally output control
The switch of code regulation capacitor array processed.
According to adjustment tube grid capacitance compensation method proposed by the present invention, analog circuit can also be used to realize to grid electricity
The compensation of appearance.But digital circuit compensation proposed by the present invention has the advantage that：(1) digital analog converter is used by the simulation of detection
Voltage is changed into data signal, has the characteristics of precision is high, anti-interference strong；(2) when adjustment pipe is operated in two operated adjacents just
When state edge, analog circuit constant may convert compensating electric capacity value, it is difficult to provide stable result；Digital circuit can be with
Differentiate this case and solve.(3) folding of capacitor array switch may have an impact to LDO, and digital circuit can lead to
Cross correct SECO and ensure that regulation process is more reliable.
The foregoing is only a preferred embodiment of the present invention, but protection scope of the present invention be not limited thereto,
Any one skilled in the art the invention discloses technical scope in, the change or replacement that can readily occur in,
It should all be included within the scope of the present invention.Therefore, protection scope of the present invention should be with scope of the claims
It is defined.
Claims (6)
1. a kind of low pressure difference linear voltage regulator using digital circuit compensating electric capacity, it is characterised in that using miller compensation
In low differential voltage linear voltage stabilizer circuit, using the output voltage of voltage detecting circuit detection error amplifier, the voltage of detection is defeated
Enter digital-to-analog converter and be converted to data signal, data signal input Digital Logic control circuit, Digital Logic control circuit is sentenced
The working condition of disconnected adjustment pipe, the capacitance size for now needing to compensate, and output control signal are drawn according to the information to prestore, is adjusted
The break-make of capacitor array is saved, the total capacitance of guarantee adjustment tube grid keeps constant, and the capacitor array includes some groups of branch in parallel
Road, every group of branch route an electric capacity and a switch is composed in series, and each branch road is connected to adjustment tube grid and power supply VDDBetween, institute
State and switched on-off in each branch road of output control of Digital Logic control circuit so that electric capacity accesses tune as requested in each branch road
Homogeneous tube grid, so as to adjust the capacitance size being connected on adjustment tube grid, when the electric capacity for adjusting tube grid node becomes small, increase
The capacitive branch that adjunction enters so that total capacitance becomes big；When the electric capacity for adjusting tube grid node becomes big, the electric capacity branch of access is reduced
Road so that total capacitance diminishes.
2. the low pressure difference linear voltage regulator of digital circuit compensating electric capacity is used according to claim 1, it is characterised in that described
Using in the low differential voltage linear voltage stabilizer circuit of miller compensation, VOUTIt is load supplying for output voltage, equivalent load resistance RL
With equivalent load capacitance and be connected in VOUTBetween GND, pass through sampling resistor RF1With resistance RF2To VOUTPartial pressure sampling is carried out,
Obtain feedback voltage VF, VFWith reference voltage VREFIt is compared, control voltage V is obtained after error amplifier AMP amplificationsC,
VCControl adjustment pipe M1Grid voltage, the electric capacity C for miller compensationCWith the resistance R for eliminating zero pointCIt is connected on VCWith
VOUTBetween.
3. the low pressure difference linear voltage regulator of digital circuit compensating electric capacity is used according to claim 1, it is characterised in that described
Voltage detecting circuit is connected with filter amplification circuit, and institute's detectable voltage signals are filtered, are transmitted to digital-to-analog converter after amplification.
4. the low pressure difference linear voltage regulator of digital circuit compensating electric capacity is used according to claim 1, it is characterised in that described
Digital Logic control circuit be connected with voltage detecting circuit it is adjusted, make its output meet digital-to-analog converter input will
Ask.
5. the low pressure difference linear voltage regulator of digital circuit compensating electric capacity is used according to claim 1, it is characterised in that described
The working condition of adjustment pipe includes sub-threshold region, saturation region or linear zone.
6. the low pressure difference linear voltage regulator of digital circuit compensating electric capacity is used according to claim 1, it is characterised in that described
Equivalent capacity of the pipe under different working condition is adjusted to determine by circuit design early stage and emulation.
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| CN107491131B (en) * | 2017-10-16 | 2023-02-28 | 佛山科学技术学院 | Digital-analog hybrid control multi-loop LDO circuit |
| CN114166905B (en) * | 2021-10-19 | 2022-11-18 | 清华大学 | 68dB dynamic range potentiostat for electrochemical biosensing |
| TWI825515B (en) * | 2021-11-26 | 2023-12-11 | 瑞昱半導體股份有限公司 | Digital low-dropout regulator and control method thereof |
| CN116500369B (en) * | 2023-06-28 | 2023-09-15 | 深圳安森德半导体有限公司 | DCDC voltage stabilizer voltage detection method |
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| US7173402B2 (en) * | 2004-02-25 | 2007-02-06 | O2 Micro, Inc. | Low dropout voltage regulator |
| US7821238B1 (en) * | 2008-06-09 | 2010-10-26 | National Semiconductor Corporation | Feedback loop compensation for buck/boost switching converter |
| CN101957628B (en) * | 2009-07-17 | 2014-01-29 | 上海沙丘微电子有限公司 | Self-adaption zero-frequency compensation circuit in low-voltage difference linear voltage regulator |
| CN101819448A (en) * | 2010-04-02 | 2010-09-01 | 上海北京大学微电子研究院 | Linear voltage regulator |
| CN101847028B (en) * | 2010-04-14 | 2012-03-28 | 广州市广晟微电子有限公司 | Dynamic compensation circuit with ultra-low power consumption and linear regulator with the same |
| US8169203B1 (en) * | 2010-11-19 | 2012-05-01 | Nxp B.V. | Low dropout regulator |
| CN103105883A (en) * | 2011-11-11 | 2013-05-15 | 中国科学院微电子研究所 | Linear voltage regulator with load detection circuit and dynamic zero compensation circuit |
| CN102707755B (en) * | 2012-05-30 | 2016-12-14 | 西安航天民芯科技有限公司 | A kind of linear voltage regulators of built-in compensation electric capacity |
| CN104076861A (en) * | 2014-07-18 | 2014-10-01 | 周国文 | Bandgap reference of improved mixed-signal circuit |
| CN104393865B (en) * | 2014-08-07 | 2017-07-18 | 杭州硅星科技有限公司 | A kind of quick startup digital output buffer and its control method |
| CN104238613B (en) * | 2014-09-01 | 2015-10-28 | 东南大学 | A kind of digital circuit low pressure difference linear voltage regulator |
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